Synthesis of CC-1065/duocarmycin analogs

ABSTRACT

The present invention relates to a method for the synthesis of the dihydroindole C-ring found in CC-1065/duocarmycin analogs.

This application is a 371 of PCT/US99/25992 Filed Dec. 8, 1998 whichclaims benefit of provisional application No. 60/067,960 Filed Dec. 8,1997.

TECHNICAL FIELD

The present invention relates to a method for the synthesis of thedihydroindole C-ring found in CC-1065/duocarmycin analogs. Moreparticularly, the invention comprises the 5-exo-trig radical cyclizationof an aryl halide onto a tethered vinyl chloride forming thedihydroindole C-ring with chlorine installed as a suitable leaving groupfor subsequent cyclopropane spirocyclization. The versatility of thisapproach is examined in the context of six CC-1065/duocarmycin analogspreviously synthesized in this laboratory.

BACKGROUND

CC-1065 (1; Chidester et al. J. Am. Chem. Soc. 1981, 1-3, 7629) and theduocarmycins 2 (Ichimura et al. J. Antibiot. 1990, 43, 1037) and 3(Takahashi et al. J. Antibiot. 1988, 41, 1915; Yasuzawa et al. Chem.Pharm. Bull. 1995, 43, 378) are the parent members of a potent class ofantitumor antibiotics that derive their biological properties throughreversible, sequence selective alkylation of DNA (For a review ofmechanistic aspects see: Boger, et al. Angew. Chem., Int. Ed. Engl.1996, 35, 230).

Since their disclosure, synthetic efforts have focused on the naturalproducts as well as a great number of rationally designed analogs (For areview of synthetic efforts see: Boger et al. Chem. Rev., 1997, 97,787). These analogs have served define the fundamental principlesunderlying the relationships between structure, chemical reactivity andbiological properties within this family, and have advanced theunderstanding of the origin of sequence selectivity and the catalysis ofthe DNA alkylation reaction by 1-3 (Boger et al. J. Am. Chem. Soc. 1997,119, 4977; Boger et al. J. Am. Chem. Soc. 1997, 119, 4987; Boger et al.Biorg. Med. Chem. 1997, 5, 263; Warpehoski et al. J. Am. Chem. Soc.1994, 116, 7573; Warpehoski et al. J. Am. Chem. Soc. 1995, 117, 2951).

Common synthetic routes to many of the duocarmycin and CC-1065 analogsincorporate the same transformation via a four step procedurehighlighted by an in-situ trap of a primary radical with TEMPO(TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxy free radical) followed byits reductive removal and conversion to the chloride as depicted for thesynthesis of CBI (Boger et al. J. Org. Chem. 1995, 60, 1271) asillustrated in FIG. 4.

It would be beneficial to have a more direct and higher yieldingtransformation to obtain the dihydroindole C-ring found inCC-1065/duocarmycin analogs. What is needed, therefore, is an efficientand general method for the synthesis of the dihydroindole C-ring foundin CC-1065/duocarmycin analogs with less steps than the standard fourstep TEMPO procedure as described above.

SUMMARY OF THE INVENTION

One aspect of the invention is directed to a 2 step synthesis of thedihydroindole C-ring found in CC-1065/duocarmycin analog. An aryl halideis alkylated with 1,3-dichloropropene and a catalytic amount ofn-tetrabutylammonium iodide for forming a vinyl chloride. The vinylchloride is then cyclized under conditions using tribuytyl tin hydride,catalytic AIBN and toluene as the solvent for forming the dihydroindoleC-ring of the CC-1065/duocarmycin analog.

Another aspect of the invention is directed to the following compounds:

DESCRIPTION OF FIGURES

FIG. 1 shows CC-1065 (1) and the duocarmycins (2) and (3). The compoundsare parent members of a potent class of antitumor antibiotics.

FIG. 2 shows CBI (4) (5), CPyI (6), desmethyl-CPI (7), iso-CBI (8), andthe mitomycin-hybrid (9) which are compounds of interest in thisapplication.

FIG. 3 shows the novel intramolecular aryl radical cyclization onto atethered vinyl chloride to install the dihydroindole C ring withchlorine installed as a suitable leaving group for subsequentcyclopropane spirocyclization.

FIG. 4 shows the standard four step procedure highlighted by an in-situtrap of a primary radical with TEMPO(TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxy free radical) followed byits reductive removal and conversion to the chloride as depicted for thesynthesis of CBI.

FIG. 5 illustrates the transformation from compound 10a to 12a and thesubsequent formation of a cyclopropyl ring.

FIG. 6 shows a table which illustrates the results of the two-stepsynthesis of 3-chloro-methylindolines with the following conditions: aNaH, 1,3-dichloropropene, DMF, 25° C.; b NaH, 1,3-dichloropropene,nBu₄NI, DMF, 25° C.; c AIBN (cat.), Bu₃SnH, benzene, 60-75° C.; d AIBN(cat.), Bu₃SnH, toluene, 90° C. wherein each compound uses the sametransformation as shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to a two-step transformation directed to thesynthesis of 6 CC-1065/duocarmycin analogs using a novel intramoleculararyl radical cyclization onto a vinyl chloride to form the dihydroindoleC-ring found in 6 CC-1065/duocarmycin analogs. This transformationrepresents a potential two-step improvement to the synthetic route tomany other analogs, which most recently incorporated the sametransformation via a four step procedure highlighted by an in-situ trapof a primary radical with TEMPO(TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxy free radical) followed byits reductive removal and conversion to the chloride as depicted for thesynthesis of CBI (Boger et al. J. Org. Chem. 1995, 60, 1271) asillustrated in FIG. 4.

Patel et al. describes the synthesis of an analog named Oxa-duocarmycinSA which utilizes a novel intramolecular aryl radical cyclization onto atethered vinyl chloride to install the dihydroindole C ring withchlorine installed as a suitable leaving group for subsequentcyclopropane spirocyclization as described in FIG. 3.

Application of this improved two-step transformation to the syntheticroutes reported for a number of the analogs synthesized in thislaboratory would serve to establish the versatility of this approach tothe synthesis of CC-1065 and duocarmycin analogs.

With this goal in mind, the C-ring construction for CBI (4; Boger et al.J. Org. Chem. 1995, 60, 1271, CCBI (5; Boger et al. J. Org. Chem. 1996,61, 4894), CPyI (6), desmethyl-CPI (7), iso-CBI (8), and themitomycin-hybrid (9) was investigated. The appropriately functionalizedaryl halides (10a-g), which were obtained either through directelectrophilic halogenation (entries 1-5) or directed ortho metallation(entries 6 and 7) and halide quench, were alkylated with 1,3dichloropropene to complete the radical cyclization precursors (11a-g)in high yields. Treatment with BU₃SnH and a catalytic amount of AIBN(AIBN=2,2′-azobisisobutyronitrile) with heating in benzene or toluenevery cleanly effected 5-exo-trig radical cyclization to form the3-chloromethyl indoline C-ring present in each of the analogs (12a-g) asillustrated in FIG. 6.

This two-step transformation works well with benzene, naphthalene,indole and quinoline derivatives, aryl iodides as well as aryl bromides,with little to no deterioration in the consistently high yields for bothsteps. Brief optimization efforts revealed that higher yields maysometimes be obtained with addition of n-Bu₄NI to the alkylationreaction, as well as substitution of toluene and higher reactiontemperature for benzene. It was observed, as also noted by Patel et al.that deoxygenation of the solvent prior to radical cyclization mayenhance both the rate and yield of the reaction.

In summary, this novel intramolecular aryl radical cyclization onto avinyl chloride, as introduced by Patel, was successfully applied to theC-ring synthesis of 6 CC-1065/duocarmycin analogs. This application haseffectively shortened the synthesis of each of these analogs by twosteps. Clearly the versatility of this approach, combined with the highconversions for both steps, assure its use in future rational analogdesign in the CC-1065/duocarmycin family of antitumor antibiotics.

While a preferred form of the invention has been shown in the drawingsand described, since variations in the preferred form will be apparentto those skilled in the art, the invention should not be construed aslimited to the specific form shown and described, but instead is as setforth in the following claims.

Experimental Protocals

General ¹H and ¹³C nmr spectra were recorded either on a Bruker AM-250,a Bruker AMX-400 or a Bruker AMX-500 spectrometer. Residual proticsolvent CHCl₃ (δ_(H)=7.26 ppm, δ_(c)=77.0), d₄-methanol (δ_(H)=3.30 ppm,δ_(c)=49.0) and D₂O (δ_(H)=4.80 ppm, δ_(c) (of CH₃CN)=1.7 ppm) or TMS(δ_(H)=0.00 ppm) were used as internal reference. Coupling constantswere measured in Hertz (Hz). HRMS were recorded using FAB method in am-nitrobenzylalcohol (NBA) matrix doped with NaI or CsI. Infraredspectra were recorded on a Perkin-Elmer FTIR 1620 spectrometer.Enantiomeric excess was determined by HPLC using a Daicel ChemicalIndustries CHIRALPAK AD column. Optical rotations were measured with anOptical Activity AA-1000 polarimeter. Melting points were taken on aThomas Hoover capillary melting point apparatus and are uncorrected.Column chromatography was performed on Merck Kieselgel 60 (230-400mesh). Analytical thin layer chromatography was performed usingpre-coated glass-backed plates (Merck Kieselgel F₂₅₄) and visualized bycerium molybdophosphate or ninhydrin. Diethyl ether, tetrahydrofuran(THF) and toluene (PhCH₃) were distilled from sodium-benzophenone ketyl,dichloromethane (DCM) and acetonitrile from calcium hydride. Othersolvents and reagents were purified by standard procedures if necessary.

General Experimental Procedure for Individual Synthesis of 12a-g asShown in FIG. 6

A solution of the aryl iodide (one of 10a-g as shown in FIG. 6 obtainedfrom the sources or conditions as described herein; aryl iodide isobtained from the following sources:) in anhydrous DMF (0.1M) at 0° C.was treated with NaH (2.0 equiv.) in small portions. The resultingsuspension was stirred 15 min and treated with neat 1,3-dichloropropene(5.0 equiv) in a slow dropwise manner, followed by catalytic Bu₄NI (0.1equiv.; n-tetrabutylammonium iodide ). The reaction mixture was warmedto 25° C. and stirred for 12 h. The reaction mixture was quenched withthe addition of 5% aqueous NaHCO₃, and the aqueous layer was extractedwith EtOAc. The combined organic extracts were washed with H₂O, dried(Na₂SO₄) and concentrated under reduced pressure. The crude was purifiedby flash column chromatography. A solution of one of 11a-g in anhydrousbenzene (0.1M; alternatively substitution of toluene and higher reactiontemperature can optimize yield, due to higher temperatures) was treatedwith Bu₃SnH (1.05 equiv.) and catalytic AIBN (0.1 equiv.) anddeoxygenated with a stream of dry N₂ gas. The solution was heated to 80°C. for 2 h and concentrated in vacuo. The crude was purified by flashcolumn chromatography to form one of compounds 12a-g.

Synthesis of Cyclopropane via Spirocyclization

The chlorine group of the dihydroindole C-ring is installed as asuitable leaving group for cyclopropane spirocyclization. Methodologiesfor subsequent spirocyclization and further aklyation of the resultantcyclopropane C-ring system to the DNA portion of CC-1065 and theduocarmycins is well known in the art. A representative spirocyclizationis accomplished via treatment of 12(a-g) with NaH (3 equiv, THF, 0° C.,30 min) to provide (4-9; as shown in FIG. 2). Similarly, acid-catalyzeddeprotection of 12(a-g) (3N HCl-EtOAc, 25° C., 20 min) followed byspirocyclization of the crude indoline hydrochloride salt upon exposureto 5% aqueous NaHCO₃-THF (1:1, 25° C., 1.5 h, 93%) can also provide(4-9; as shown in FIG. 2).

Synthesis of Compounds 4-9 as Shown in FIG. 2

A solution of 12(a-g; one of the compounds in FIG. 6; obtained from thesources or conditions as described herein) (1.5 mg, 4.1 μmol) intetrahydrofuran-dimethylformamide (3:1, 200 μL) at 0° C. under N₂ wastreated with suspension of NaH (0.5 mg, 60% in an oil dispersion, 12μmol, 3 equiv). The reaction mixture was allowed to stir at 0° C. andfor 30 min before the addition of pH 7 phosphate buffer (0.2 M, 250 μL)and 2 mL of tetrahydrofuran. The organic layer was dried (Na₂SO₄) andconcentrated in vacuo. Chromatography (SiO₂, 20-30% Ethylacetate-hexanegradient elution) afforded (4-9; as shown in FIG. 2): AlternativeSpyrocyclization: 12(a-g; one of the compounds) (5 mg, 1.37 μmol) wastreated with anhydrous 3N HCl-Ethylacetate (0.4 mL) at 24° C. for 20min. The solvent was removed in vacuo to afford the crude, unstableamine hydrochloride. This residue was treated with 5% aqueous NaHCO₃(0.4 mL) and tetrahydrofuran (0.4 mL) at 24° C. under N₂, and the twophase mixture was stirred for 1.5 h (24° C.). The reaction mixture wasextracted with Ethylacetate (3×2 mL) and the combined extracts werewashed with H₂O (2 mL), dried (Na₂SO₄) and concentrated in vacuo.Chromatography (SiO₂, 10% CH₃OH—CH₂Cl₂) afforded (4-9; as shown in FIG.2).

2,4-(Dimethoxy)-3-(methyl)-methoxymethyl phenyl ether (101)

A solution of 2,4-(dimethoxy)-3-methylphenol (1.0 g, 5.95 mmol) in 60 mLof anhydrous DMF at 0° C. was treated with NaH (357 mg, 9.91 mmol) inseveral portions over 5 min. After 10 min, Bu₄NI (219 mg, 0.60 mmol) wasadded followed by the dropwise addition of ClCH₂OCH₃ (0.68 mL, 8.91mmol). The reaction mixture was stirred at 25° C. for 36 h before thereaction was quenched by the slow addition of 30 mL of H₂O. The aqueouslayer was extracted with EtOAc (3 (30 mL). The organic layers werecombined, washed with 10% aqueous NaHCO₃ (50 mL) and H₂O (4(20 mL),dried (Na₂SO₄), and concentrated under reduced pressure. Flashchromatography (SiO₂, 3 (10 cm, 10% EtOAc/hexane) provided 101 (1.11 g,88%) as a light yellow oil: ¹H NMR (CDCl₃, 250 MHz) δ6.92 (d, J=8.8 Hz,1H), 6.51 (d, J=8.8 Hz, 1H), 5.13 (s, 2H), 3.79 (s, 3H), 3.76 (s, 3H),3.50 (s, 3H), 2.13 (s, 3H); ¹³C NMR (CDCl₃, 62.5 MHz) δ153.5, 149.2,144.3, 121.0, 114.4, 105.3, 96.0, 60.4, 56.0, 55.7, 8.9; IR (film)ν_(max) 2937, 2833, 1595, 1487, 1440, 1420 cm⁻¹; FABHRMS (NBA) m/z212.1040 (C₁₁H₁₆O₄ requires 212.1049).

2,4-(Dimethoxy)-3-(methyl)-5-(nitro)-methoxymethyl phenyl ether (102)

A solution of 101 (1.11 g, 5.21 mmol) in 18 mL freshly distilled Ac₂O at0° C. was treated with Cu(NO₃)₂.2.5 H₂O (2.41 g, 10.4 mmol) in severalportions over 5 min. The reaction mixture was stirred for 2 h at 0° C.,then 1 h at 25° C. before the reaction was poured over H₂O (50 mL) andextracted with EtOAc (3 (30 mL). The combined organic layers were washedwith saturated aqueous NaCl (50 mL), dried (Na₂SO₄), and concentratedunder reduced pressure. The crude light yellow oil (1.18 g, 88%) wascarried on to the next transformation: ¹H NMR (CDCl₃, 250 MHz) δ7.54 (s,1H), 5.18 (s, 2H), 3.87 (s, 3H), 3.81 (s, 3H), 3.48 (s, 3H), 2.21 (s,3H); ¹³C NMR (CDCl₃, 62.5 MHz) δ153.0, 147.8, 145.8, 138.9, 128.2,110.5, 95.3, 61.8, 60.5, 56.2, 9.5; IR (film) ν_(max) 2942, 2829, 1522,1481, 1344, 1280, 1246 cm⁻¹; FABHRMS (NBA) m/z 258.0977 (C₁₁H₁₅NO₆+H⁺requires 258.0978).

5-(Amino)-2,4-(dimethoxy)-3-(methyl)-methoxymethyl phenyl ether (103)

A solution of 102 (1.18 g, 4.57 mmol) in 90 mL moist ether (8:2:1Et₂O:EtOH:H₂O) was cooled to 0° C., and treated with freshly preparedAl-Hg (1.23 g Al, 45.7 mmol) in small 1 (1 cm pieces. The reactionmixture was stirred vigorously for 0.5 h at 0 (C., then 1 h at 25 (C.The reaction mixture was then filtered through Celite, and the Celitewas washed thoroughly with Et₂O (5 (20 mL). The solution was then washedwith saturated aqueous NaCl (100 mL), dried (Na₂SO₄), and concentratedunder reduced pressure to afford 103 (0.88 g, 85%) as a crude brown oil,which was immediately carried on to the next step: ¹H NMR (CDCl₃, 250MHz) δ6.42 (s, 1H), 5.11 (s, 2H), 3.70 (s, 3H), 3.66 (s, 3H), 3.56 (m,2H), 3.47 (s, 3H), 2.16 (s, 3H); ¹³C NMR (CDCl₃, 250 MHz) δ147.0, 140.4,140.3, 135.8, 125.4, 102.0, 95.4, 60.6, 59.4, 56.0, 9.34; IR (film)ν_(max) 3446, 3359, 2935, 2826, 1617, 1492, 1358 cm⁻¹; ESIMS m/z 228(C₁₁H₁₇NO₄+H⁺ requires 228).

[N-(tert-Butyloxycarbonyl)amino]-2,4-(dimethoxy)-5-(methoxymethoxy)-3-methylbenzene(104)

A solution of crude 102 (0.88 g, 3.85 mmol) in 40 mL anhydrous THF wastreated with BOC₂O (1.73 g, 7.72 mmol) and the reaction mixture waswarmed at reflux (65 (C.) for 18 h. The solvents were removed underreduced pressure, and flash chromatography (SiO₂, 3 (10 cm, 10%EtOAc/hexane) provided pure 104 as a yellow oil (0.96 g, 76%): ¹H NMR(CDCl₃, 250 MHz) δ7.72 (br s, 1H), 6.86 (br s, 1H), 5.18 (s, 2H), 3.75(s, 3H), 3.67 (s, 3H), 3.51 (s, 3H), 2.19 (s, 3H), 1.50 (s, 9H); ¹³C NMR(CDCl₃, 100 MHz) δ152.7, 146.4, 143.6, 141.6, 127.8, 124.8, 105.3, 95.5,80.4, 60.5, 60.4, 56.4, 28.3, 9.5; IR (film) ν_(max) 3437, 3341, 2977,2935, 1731, 1519, 1454, 1422, 1397 cm⁻¹; FABHRMS (NBA/CsI) m/z 460.0723(C₁₆H₂₅NO₆+Cs⁺ requires 460.0736).

[N-(tert-Butyloxycarbonyl)amino]-2,4-(dimethoxy)-6-(iodo)-5-(methoxymethoxy)-3-methylbenzene (10 g)

A solution of 104 (0.55 g, 1.67 mmol) in 6.6 mL anhydrous THF was cooledto −25 (C. and treated with TMEDA (0.94 mL, 6.18 mmol) followed byn-BuLi (2.5 mL of a 2.5 M solution in hexane, 6.18 mmol) in a slowdropwise manner. The resulting gold solution stirred for 2 h at −25 (C.The reaction mixture was treated with 1-chloro-2-iodoethane (0.45 mL,6.18 mmol) and stirred for 15 min at 25 (C. The reaction was dilutedwith H₂O (50 mL) and extracted with Et₂O (3 (30 mL), and the combinedorganic extracts were washed with saturated aqueous NaCl, dried(Na₂SO₄), and concentrated under reduced pressure. Flash chromatography(SiO₂, 2.5 (10 cm, 20% EtOAc/hexane) yielded 11 g (560 mg, 74%) as acolorless oil: ¹H NMR (CDCl₃, 400 MHz) δ5.99 (br s, 1H), 5.10 (s, 2H),3.75 (s, 3H), 3.69 (s, 3H), 3.65 (s, 3H), 2.17 (s, 3H), 1.49 (s, 9H);¹³C NMR (CDCl₃, 100 MHz) δ153.6, 151.8, 150.5, 146.9, 129.3, 126.7,99.1, 95.8, 80.6, 60.5, 60.3, 58.5, 28.3, 9.8; IR (film) ν_(max) 3321,2975, 2936, 1722, 1485, 1455, 1390 cm⁻¹; FABHRMS (NBA/CsI) m/z 585.9688(C₁₆H₂₄INO₆+Cs⁺ requires 585.9703).

[N-(tert-Butyloxycarbonyl)-N-(3-chloro-2-propen-1-yl)amino]-2,4-(dimethoxy)-6-(iodo)-5-(methoxymethoxy)-3-methylbenzene(11 g).

A solution of 10 g (0.610 g, 1.34 mmol) in 13.4 mL anhydrous DMF wascooled to 0 (C., and treated with NaH (60% dispersion in oil, 121 mg,4.03 mmol) in small portions. The resulting suspension was stirred for15 min and treated with neat 1,3-dichloropropene (0.52 mL, 5.5 mmol) ina slow dropwise manner, followed by catalytic n-Bu₄NI (50.0 mg, 0.13mmol). The reaction mixture was warmed to 25 (C. and stirred for 3 h.The reaction mixture was quenched with the addition of saturated aqueousNaHCO₃ (50 mL), and the aqueous layer was extracted with EtOAc (3 (30mL). The combined organic extracts were washed with H₂O (4 (50 mL),dried (Na₂SO₄), and concentrated under reduced pressure. Flashchromatography (SiO₂, 3 (10 cm, 0-20% EtOAc/hexane gradient) yielded 11g (0.681 g, 96%) as a colorless mixture of rotamers: ¹H NMR (CDCl₃, 400MHz) 2:1 rotamers δ6.15-6.03 (m, 1H), 6.00-5.90 (m, 1H), 5.11-5.03 (m,2H), 4.17-3.87 (m, 2H), 3.77 and 3.74 (s, 3H), 3.65 and 3.63 (s, 3H),3.627 and 3.622 (s, 3H), 2.14 and 2.13 (s, 3H), 1.50 and 1.34 (s, 9H);¹³C NMR (CDCl₃, 100 MHz) rotamers δ153.65 and 153.62, 152.8 and 152.1,151.0 and 150.7, 147.0 and 146.7, 134.5 and 134.0, 129.5 and 129.0,127.0 and 126.7, 121.0 and 120.6, 99.0, 97.7 and 97.3, 80.8 and 80.6,60.5 and 60.4, 60.3 and 60.2, 58.5 and 58.4, 50.4, 48.8, 28.3 and 28.2,9.9; IR (film) ν_(max) 2973, 2936, 1704, 1456, 1366 cm⁻¹; FABHRMS(NBA/CsI) m/z 659.9655 (C₁₉H₂₇ClINO₆+Cs⁺ requires 659.9626).

3-Bromo-8-hydroxy-6-nitroquinoline (210)

A solution of 2-bromoacrolein (5 g, 37.0 mmol, 1 equiv) in 110 mLglacial acetic acid at 25° C. was titrated to the appearance of a faintreddish color with bromine (ca. 5.9 g, 37.0 mmol, 1 equiv).2-Hydroxy-4-nitroaniline (209, 5.7 g, 37.0 mmol, 1 equiv) was added, andthe solution was gradually heated to 100 (C. The solution was cooled to25 (C. after one hour. Filtering and neutralization of the precipitatewith 1 M sodium phosphate buffer (pH 7, Na₂HPO₄—NaH₂PO₄) afforded 9.2 g(9.95 g theoretical, 92%) of 210 as a light yellow solid: mp 240-241 (C;¹H NMR (CDCl₃, 400 MHz) δ8.93 (d, J=2.0 Hz, 1H), 8.50 (d, J=2.0 Hz, 1H),8.23 (d, J=2.2 Hz, 1H), 8.18 (s, 1H), 7.92 (s, J=2.3 Hz, 1H); ¹³C NMR(DMSO, 62.5 MHz) δ155.1, 152.1, 146.3, 139.5, 139.1, 128.7, 119.1,113.5, 105.1; IR (film) (_(max) 3408 (br), 3089, 1587, 1553, 1519, 1476,1389, 1350, 1297, 1263, 1210, 1133, 1079, 929, 931, 839, 804, 734, 633cm⁻¹; ESIMS m/z 269 (M+H⁺, C₉H₃BrO requires 269); Anal. Calcd forC₉H₃BrO: C, 40.18; H, 1.87; N, 10.41. Found: C, 40.21; H, 1.91; N, 9.98.

8-(Benzyloxy)3-bromo-6-nitroquinoline (211)

A solution of 210

(13.7 g, 51 mmol, 1 equiv) in anhydrous DMF (150 mL) was cooled to 4 (C.under nitrogen and treated with KI (1.7 g, 10 mmol, 0.2 equiv) andsodium hydride (60% dispersion in oil, 2.24 g, 56 mmol, 1.1 equiv).Benzyl bromide (7.3 mL, 6.1 mmol, 1.2 equiv) was added after 30 min andthe reaction was allowed to warm to 25 (C. After 24 h, the reactionvolume was reduced by one-third in vacuo and EtOAc (200 mL) was added.The reaction mixture was poured on H₂O (200 mL) and extracted with EtOAc(3 (100 mL). The combined organic extracts were washed with saturatedaqueous NaCl (1 (40 ml), dried (Na₂SO₄) and concentrated. Flashchromatography (SiO₂, 5.5 (20 cm, 50-100% CH₂Cl₂-hexane) afforded 211(15.63 g, 18.32 g theoretical, 85%) as a yellow solid: mp 170 (C; ¹H NMR(CDCl₃, 400 MHz) δ9.06 (d, J=2.2 Hz, 1H), 8.44 (d, J=2.2 Hz, 1H), 8.25(d, J=2.2 Hz, 1H), 7.83 (d, J=2.2 Hz, 1H), 7.52 (app d, J=7.4 Hz, 2H),7.38 (m, 2H), 7.32 (m, 1H), 5.47 (s, 2H); ¹³C NMR (CDCl₃, 62.5 MHz)δ155.4, 153.3, 146.4, 140.3, 138.8, 135.0, 128.7 (2C), 128.6, 128.4(2C), 127.5, 119.9, 115.1, 103.3, 71.4; IR (film) (_(max) 3082, 3055,2933, 2871, 1609, 1567, 1519, 1476, 1450, 1375, 1338, 1311, 1252, 1135,1093, 976, 912, 842, 741 cm⁻¹; FABHRMS (NBA/NaI) m/z 359.0040 (M+H⁺,C₁₆H₁₁BrN₂O₃ requires 359.0031). Anal. Calcd for C₁₆H₁₁BrN₂O₃: C, 53.50;H, 3.09; N, 7.80. Found: C, 53.81; H, 3.23; N, 7.48.

3-(Benzyloxy)-3-bromo-6-N-(tert-butyloxycarbonyl)aminoquinoline (212)

A solution of 211 (200 mg, 0.56 mmol, 1 equiv) in EtOAc (1.1 mL) at 25(C. was treated with SnCl₂—2H₂O (628 mg, 2.78 mmol, 5 equiv). Thereaction mixture was heated to 70 (C. under nitrogen until an orangeslurry formed (ca. 0.5 h). After cooling to 25 (C., the reaction mixturewas poured on ice and made basic with 1N NaOH. The aqueous layer wasfiltered and extracted with EtOAc (3 (15 mL). The combined organiclayers were treated with saturated aqueous NaCl (1 (10 mL), dried(Na₂SO₄) and concentrated. The yellow solid was placed under vacuum for0.5 h and then dissolved in anhydrous dioxane (5 mL) and treated withdi-tert-butyl dicarbonate (490 mg, 2.25 mmol, 4.0 equiv) andtriethylamine (156 μL, 1.12 mmol, 2.0 equiv). The reaction mixture waswarmed to 70° C. under argon for one day. After cooling, the solvent wasremoved in vacuo. Chromatography (SiO₂, 3 (13 cm, 25% EtOAc-hexane)afforded 212 (179 mg, 240 mg theoretical, 74%) as a light yellow solid:mp 162 (C; ¹H NMR (CDCl₃, 500 MHz) δ8.77 (d, J=2.0 Hz, 1H), 8.13 (d,J=2.5 Hz, 1H), 7.47 (app d, J=7.5 Hz, 2H), 7.42 (d, J=2.0 Hz, 1H), 7.35(m, 2H), 7.28 (m, 1H), 7.01 (d, J=2.0 Hz, 1H), 6.61 (s, 1H), 5.37 (s,2H), 1.51 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz) δ154.9, 152.4, 148.3, 137.9,136.3, 136.2, 135.4, 131.0, 128.6 (2C), 128.0, 127.3 (2C), 118.6, 104.7,103.6, 81.1, 70.9, 28.3 (3C); IR (film) (_(max) 3354, 2971, 2919, 1807,1766, 1724, 1621, 1450, 1367, 1310, 1253, 1217, 1160, 1123, 1061, 843,771, 699, 657 cm⁻¹; FABHRMS (NBA/CsI) m/z 429.0825 (M+H⁺, C₂₁H₂₁BrN₂O₃requires 429.0814).

n-Butyl8-(benzyloxy)-6-N-(tert-butyloxycarbonyl)aminoquinoline-3-carboxylate(213)

A solution of 212 (4.4 g, 10.1 mmol, 1 equiv) in 85 mL n-BuOH was cooledto −78 (C. and degassed under vacuum. Pd(PPh₃)₄ (1.2 g, 1.0 mmol, 0.1equiv) and n-BU₃N (2.9 mL, 12.1 mmol, 1.2 equiv) were added and thesolution was purged with nitrogen. The reaction mixture was then flushedwith carbon monoxide and then slowly heated to 100 (C. under a COatmosphere. Upon complete reaction (ca. 12 h), 50 mL H₂O and 50 mLsaturated aqueous NH₄Cl were added. The organic layer was separated andthe aqueous layer was extracted with EtOAc (3 (50 mL). The combinedorganic layers were washed with saturated aqueous NaCl (1 (40 mL), dried(Na₂SO₄) and concentrated. Chromatography (SiO₂, 5.5 (20 cm, 25%EtOAc-hexane) afforded 213 (3.55 g, 4.55 g theoretical, 78%) as a yellowsolid: mp 135-136 (C; ¹H NMR (CDCl₃, 400 MHz) δ9.31 (d, J=2.0 Hz, 1H),8.66 (d, J=2.1 Hz, 1H), 7.61 (d, J=1.8 Hz, 1H), 7.49 (app d, J=7.4 Hz,2H), 7.35 (app t, J=7.2 Hz, 2H), 7.29 (m, 1H), 7.11 (d, J=2.1 Hz, 1H),6.64 (br s, 1H), 5.39 (s, 2H), 4.38 (t, J=6.6 Hz, 2H), 1.78 (m, 2H),1.52 (s, 9H), 1.49 (m, 2H, buried under 1.52 ppm), 0.98 (t, J=7.4 Hz,3H); ¹³C NMR (acetone d₆, 100 MHz) δ165.7, 155.7, 153.5, 146.8, 139.8,139.5, 137.8, 137.7, 129.5, 129.1 (2C), 128.6, 128.4 (2C), 124.8, 107.1,106.9, 80.4, 71.2, 65.5, 31.3, 28.3 (3C), 19.8, 13.9. IR (film) (_(max)3222, 3049, 2958, 2930, 2876, 1717, 1617, 1544, 1503, 1430, 1362, 1271,1239, 1157, 1065 cm⁻¹; FABHRMS (NBA/CsI) m/z 451.2249 (M+H⁺, C₂₆H₃₀N₂O₅requires 451.2233).

Methyl-8-(benzyloxy)-6-N-(tert-butyloxycarbonyl)aminoquinoline-3-carboxylate(214)

A solution of 213 (2.9 g, 6.4 mmol, 1.0 equiv) in 70 mL MeOH was cooledto 4 (C. under nitrogen and treated with LiOMe (275 mg, 7.1 mmol, 1.1equiv). The reaction mixture was allowed to warm to 25 (C. after 20 min.Upon complete reaction (ca. 1.5 h), 100 mL H₂O was added. The organiclayer was separated and the aqueous layer was extracted with EtOAc (3(30 mL). The organic layers were combined, washed with saturated aqueousNaCl (1 (30 mL), dried (Na₂SO₄) and concentrated. Chromatography (SiO₂,5 (19 cm, 25-30% EtOAc-hexane) afforded 214 (2.39 g, 2.63 g theoretical,91%) as a yellow solid: mp 173-174 (C; ¹H NMR (CDCl₃, 400 MHz) δ9.29 (d,J=2.0 Hz, 1H), 8.66 (d, J=2.1 Hz, 1H), 7.56 (d, J=1.8 Hz, 1H,), 7.45 (m,2H), 7.30 (m, 2H), 7.25 (m, 1H), 7.18 (d, J=2.0 Hz, 1H), 6.85 (s, 1H),5.36 (s, 2H), 3.98 (s, 3H), 1.50 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz)δ165.9, 154.6, 152.6, 146.9, 138.6, 137.9, 137.8, 136.0, 128.5, 128.4(2C), 127.9, 127.3 (2C), 123.8, 106.5, 105.5, 80.8, 70.8, 52.4, 28.2(3C); IR (film) (_(max) 3333, 3241, 2974, 1723, 1621, 1580, 1539, 1497,1431, 1390, 1364, 1277, 1231, 1164, 1126, 1103, 1062, 1000, 882, 846,795, 749, 697, 662 cm⁻¹; FABHRMS (NBA/CsI) m/z 409.1773 (M+H⁺,C₂₃H₂₄N₂O₅ requires 409.1763).

Methyl8-(benzyloxy)-6-[N-(tert-butyloxycarbonyl)amino]-5-iodoquinoline-3-carboxylate(10c)

A solution of 214 (2.13 g, 5.2 mmol, 1 equiv) in 85 mL of a 1:1 mixtureof THF—CH₃OH was cooled to 4 (C. and treated with 40 mg TsOH (or H₂SO₄)in 0.5 mL THF. N-Iodosuccinimide (1.4 g, 6.2 mmol, 1.2 equiv) in 10 mLTHF was then slowly added over 10 min. After 1.5 h, the reaction mixturewas warmed to 25 (C. and then stirred 45 h. Upon complete reaction, 100mL saturated aqueous NaHCO₃, 100 mL Et₂O, and 100 mL H₂O were added. Theorganic layer was separated and the aqueous layer was extracted withEt₂O (3 (50 mL) and EtOAc (1 (50 mL). The organic layers were combined,washed with saturated aqueous NaHCO₃ (1 (50 mL) and saturated aqueousNaCl (1 (50 mL), dried (Na₂SO₄) and concentrated. Chromatography (SiO₂,5 (19 cm, hexanes then 30% EtOAc-hexane) provided 10c (2.34 g, 2.78 gtheoretical, 84%, typically 80-88%) as a yellow solid: mp 182-183 (C.;¹H NMR (CDCl₃, 400 MHz) δ9.27 (d, J=1.9 Hz, 1H), 8.96 (d, J=1.9 Hz, 1H),8.40 (s, 1H), 7.58 (m, 2H), 7.36 (m, 2H), 7.27 (m, 1H), 7.26 (s, 1H),5.43 (s, 2H), 4.01 (s, 3H), 1.55 (s, 9H); ¹³C NMR (CDCl₃, 62.5 MHz)δ165.4, 155.0, 152.3, 147.6, 141.9, 139.8, 139.7, 135.8, 129.6, 128.5(2C), 128.1, 128.0 (2C), 125.1, 105.6, 81.7, 78.4, 71.1, 52.6, 28.2(3C); IR (film) (_(max) 3384, 2974, 1723, 1595, 1554, 1498, 1431, 1400,1359, 1328, 1262, 1226, 1149, 995, 754 cm⁻¹; FABHRMS (NBA/CsI) m/z535.0743 (M+H⁺, C₂₃H₂₃IN₂O₅ requires 535.0730).

N⁵,1-Dibenzoyl-5-amino-7-(benzyloxy)-4-iodoindole (305)

The above indole (118 mg, 0.26 mmol) was stirred in THF (1 mL) andtoluenesulfonic acid (26 mg, 0.13 mmol) was added. The solution wascooled to 0° C. and N-iodosuccinimide (71 mg, 0.312 mmol) in THF (1 mL)was added. The reaction was allowed to warm to 25° C. over 1 hr. After16 hr, a further portion of N-iodosuccinimide (15 mg, 0.065 mmol) wasadded and the reaction was stirred for a further 24 hr. Saturated sodiumbicarbonate solution (1 mL) and water (4 mL) were then added and theresulting mixture was extracted with chloroform (3×5 mL). The organiclayers were combined, dried (MgSO₄) and volatiles were removed underreduced pressure. The residue was purified by flash columnchromatography (silica, ethyl acetate/hexane 3:7, 2.5×15 cm) andcrystallized from ethyl acetate to give the expected product (305) as ayellow solid (67 mg, 45%); ¹H NMR δ(ppm) (CDCl₃) 8.15 (s, 1H, NH), 7.99(d, 2H J=Hz), 7.64 (d, 2H, J=Hz), 7.58-7.47 (m, 4H, ArH), 7.30-7.17 (m,5H, ArH), 6.58 (d, 1H, J=3.6 Hz), 4.92 (s, 2H). 13C NMR δ(ppm) 168,165.5, 147.3, 136.2, 135.8, 134.9, 134.7, 134.1, 132.2, 132.1,129.8,129.6, 129.5, 129.0, 128.4, 128.3, 128.2, 127.8, 127.7, 127.1, 127.0,122.4, 110.6, 102.1, 71.9, 70.6 IR (neat) ν_(max) 3058, 1703, 1678,1598, 1332, 1279, 1237, 695 cm⁻¹ Mass Spectrum (FAB, NAB/CsI) 705(M⁺+Cs⁺).

N⁵-Benzoyl-5-amino-7-(benzyloxy)-4-iodoindole (310)

The above iodo-compound (305) (193 mg, 0.34 mmol) was stirred indichloromethane (10 mL). Sodium methoxide in methanol (0.523 mL, 1.04mmol) was added and the solution was stirred at RT for 10 min. Water (50mL) and ethyl acetate (50 mL) were added and organic layer wasseparated, dried (MgSO₄) and evaporated to give the crude product.Chromatography (2×15 cm SiO₂, ethyl acetate/hexanes 1:3) gave the purecompound (142 mg, 89%), Rf 0.2 (SiO₂, ethyl acetate/hexanes 1:3) as acolourless solid: ¹H NMR (CDCl₃, 400 MHz) 8.61 (s, 1H, NH), 8.31(s, 1H,NH), 8.05 (s, 1H), 8.00 (d, 1H, J=6.8 Hz), 7.53 (m, 5H), 7.37 (m, 3H),7.21 (dd, 1H, J=2.8, 1.4 Hz), 6.43 (dd, 1H, J=2.7, 1.2 Hz), 5.28 (s,2H); IR (neat) ν_(max) 3290, 3010, 1658, 1573, 1535, 1355 cm⁻¹; FABHRMS(NBA-CsI) m/z 600.9408. (M+Cs⁺, C₂₂H₁₇IN₂O₂ requires 600.9389).

N⁵-Benzoyl-N⁵,1-di-(tert-butoxycarbonyl)-5-amino-7-(benzyloxy)-4-iodoindole(311)

Di-tert-butyl dicarbonate (687 mg, 3.16 mmol) and DMAP (128 mg, 1.04mmol) were added to a stirred solution of compound 310 (255 mg, 0.54mmol) in dichloromethane (6 mL). After 30 min at RT the solution wasdirectly subjected to chromatography (2×15 cm SiO₂, ethyl acetate/hexane1:4) to give the pure product (390 mg, 93%) as a colorless oil (Rf 0.80,SiO₂, ethyl acetate/hexane 1:3); ¹H NMR (CDCl₃, 400 MHz) 7.81 (d, 2H,J=6.9 Hz), 7.55 (d, 1H, J=3.6 Hz), 7.45 (m, 5H), 7.31 (m, 3H), 6.82 (s,1H), 6.57 (d, 1H, J=3.6 Hz), 5.15 (s, 2H), 1.47 (s, 9H), 1.22 (s, 9H);FABHRMS (NBA-CsI) m/z 801.0402 (M+Cs⁺, C₃₂H₃₃IN₂O₆ requires 801.0438).

N⁵,1-Di-(tert-butoxycarbonyl)-5-amino-7-(benzyloxy)-4-iodoindole (10d)

Sodium methoxide in methanol (2M, 0.224 mL, 0.44 mmol) was added to astirred solution of compound (311) (150 mg, 0.22 mmol) indichloromethane (5 mL). After 10 min at RT, water (25 mL) and ethylacetate (25 mL) were added and the organic layer was separated. Theaqueous layer was extracted with ethyl acetate (25 mL) and the combinedorganic layers were dried (MgSO₄) and concentrated. Chromatography (2×15cm SiO₂, gradient elution ethyl acetate/hexanes 1:9 to ethylacetate/hexanes 1:3) gave the pure compound (102 mg , 82%), Rf 0.8(SiO₂, ethyl acetate/hexanes 1:3) as a colourless oil: ¹H NMR (CDCl₃,400MHz) 7.83 (br s, 1H, NH), 8.00 (d, 1H, J=6.8 Hz), 7.53 (m, 3H(1H+2H), 7.37 (m, 3H), 6.84 (br s, 1H), 6.45 (d, 1H, J=3.4 Hz), 5.21 (s,2H), 1.54 (s, 9H), 1.45 (s, 9H); IR (neat) ν_(max) 3395, 2977, 1759,1727, 1603, 1577, 1517, 1367, 1346, 1228, 1154, 1111 cm⁻¹; FABHRMS(NBA-CsI) m/z 697.0176 (M+Cs⁺, C₂₅H₂₉IN₂O₅ requires 697.0176).

N⁵-(3-Chloro-2-propen-1-yl)-N⁵,1-di-((tert-butyloxy)carbonyl)-5-amino-7-(benzyloxy)-4-iodoindole(11d)

Sodium hydride (22 mg, 0.54 mmol, 3 eq, 60% dispersion) was added to astirred solution of compound (10d) (100 mg, 0.18 mmol) in DMF (5 mL).After 15 min at RT, E/Z-1,3-dichloropropene (0.025 mL, 0.27 mmol) wasadded. The solution was stirred at Rt for 1 hr. Water (50 mL) and ethylacetate (50 mL) were then added and the organic layer was separated. Theaqueous layer was extracted with ethyl acetate (50 mL) and the combinedorganic layers were dried (MgSO₄) and concentrated. Chromatography (2×15cm SiO₂, ethyl acetate/hexanes 1:9) gave the pure compound (75.4 mg ,66%) as a mixture of E and Z isomers: ¹H NMR (CDCl₃, 400 MHz) majorrotamer 7.47 (br s, 1H), 7.36 (m, 5H), 6.53 (m, 1H), 6.00 (m, 2H), 5.17(s, 2H), 4.51 (m, 1H), 4.11 (m, 1H), 1.54 (s, 9H), 1.25 (s, 9H); IR(neat) ν_(max) 2976, 1759, 1701, 1630, 1570, 1367, 1157 cm⁻¹; FABHRMS(NBA-CsI) m/z 771.0125 (M+Cs⁺, C₂₈H₃₂ClIN₂O₅ requires 771.0099).

What is claimed is:
 1. A compound represented by the followingstructure:


2. A compound represented by the following structure:


3. A compound represented by the following structure:

wherein R is a radical selected from the group consisting of H and—CH₂CHCHCl.